Spatial Variability of In Situ Soil Moisture in Iowa

Soil water content is important in agribusiness and ground water management and it is influenced by factors such as soil texture, land cover and precipitation. In this study, soil moisture data from 40 sites in Iowa (1954 to 1983) are analyzed to develop a soil moisture climatology. The hypothesis of this research is that soil characteristics, land cover and atmospheric processes, such as precipitation and evapotranspiration, impact monthly and seasonal fluctuations in volumetric water content (VWC). The 30 years of soil moisture data are used to identify mean monthly seasonal changes in VWC and the spatial patterns of VWC in Iowa. Cluster analysis is used to divide the state into 3 groups and the soil moisture patterns are analyzed for each group. In addition, precipitation data are used to explain the patterns in VWC. This study provides a better understanding of the spatial variability of soil moisture in Iowa due to the effects of precipitation and atmospheric processes.

Key Words: soil moisture, precipitation, volumetric water content, Iowa